1. Filed of the Invention
The present invention relates to a method and an apparatus for imaging a liquid-filling container in which a plurality of imaging devices each comprising a light emitting unit and a light receiving unit are provided and light from each light emitting unit is irradiated onto a liquid-filling container and the light transmitted through the container is received by each light receiving unit.
2. Description of Prior Art
The imaging of a liquid-filling container noted above is employed in a manufacturing line of various beverages such as soft drinks or alcoholic beverages in order to inspect whether the amount of liquid as the beverage filled in a container made of glass or PET is within a predetermined range or not and/or whether any foreign substance is inadvertently mixed in the beverage filled in the container or present in the container or the material forming the container or a condition of the mouth of the liquid-filling container, or whether a cap is securely fitted on the mouth of the container or not.
Conventionally, in the case of inspection of e.g. beverage by way of imaging a liquid-filling container, a single light emitting unit emits and irradiates a visible light having a wavelength of 400 to 700 nm onto the container to be transmitted therethrough to be received by a light receiving unit comprising a CCD camera for imaging of the container, so that the inspection is effected based on the image whether the surface level of the liquid inside the container is within a predetermined range or not. And, another light emitting unit is employed for emitting a visible light of the same wavelength for determination as to whether any foreign substance is mixed in the beverage or in the container or the material forming the container or not. And, still another light emitting unit is employed for emitting the visible light of the same wavelength to be reflected by the mouth of the container or the cap and this reflected light is received by a corresponding light receiving unit for determination as to the condition of the container mouth or whether the cap is properly fitted to this mouth or not.
With the conventional imaging technique above, the light emitting units for the detection of the liquid surface level, the detection of the foreign substance present in the liquid or in the container or its material and the detection of the mouth or the attached condition of the cap to the mouth all emit a visible light of a same wavelength. Accordingly, e.g. irregular reflection of the light may occur due to the shape of the liquid-filling container to interfere as a noise with the visible light for liquid surface level detection and the visible light for the cap attachment condition detection. So that, a portion of the visible light for liquid level detection may enter the light receiving unit for cap attachment detection. Conversely, a portion of the visible light for foreign substance detection or cap attachment detection can be incident on the light receiving unit for the liquid level detection. Consequently, the detection of liquid surface level, the detection of foreign substance and detection of cap attachment can not be reliably effected simultaneously.
For improving the detection precision, it is conceivable to provide a time difference between the liquid level detection, foreign substance detection and cap attachment detection, so as to effect the liquid level detection first and to effect the detection of foreign substance or cap attachment thereafter. This, however, increases the time required for detection, inviting reduction in the production efficiency.
Another conceivable method is to block the noise by changing or shielding the sites of detection between the liquid level detection and the foreign substance or cap attachment detection. This, however, increases the space required for detection. In the case of a manufacturing line of beverage for instance, this method will make it difficult to form the manufacturing line compact and will require much cost in terms of maintenance and production efficiency.
The present invention has been devised to overcome the above-described problems of the prior art. A primary object of the invention is to provide a method and an apparatus for imaging a liquid-filing container which method or apparatus allows simultaneous and highly reliable imaging of two or more kinds of condition of the container.
According to the present invention, as shown in FIGS. 1 and 3 for example, in a method and an apparatus for imaging a liquid-filling container in which a plurality of imaging devices 2, 5, 8, 20 each comprising a light emitting unit 3, 6, 9, 21 and a light receiving unit 4, 7, 10, 22 are provided and light from each light emitting unit 3, 6, 9, 21 is irradiated onto a liquid-filling container B and this light transmitted through the container is received by each light receiving unit 4, 7, 10, 22, wherein wavelengths of the lights emitted by the respective light emitting units 3, 6, 9, 21 and received by the respective light receiving units 4, 7, 10, 22 of the imaging devices 2, 5, 8, 20 for imaging the liquid-filling containers are different from each other.
With this feature, a plurality of imaging devices each comprising a light emitting unit and a light receiving unit are provided and wavelengths of the lights emitted by the respective light emitting units and received by the respective light receiving units of the imaging devices for imaging the liquid-filling containers are different from each other. Therefore, there occurs no such trouble as light irradiated from one light emitting unit enters a light receiving unit not corresponding to this light emitting unit. Consequently, two or more kinds of conditions of the liquid-filing container may be imaged simultaneously and reliably.
According to the present invention, as shown in FIGS. 1 and 3 for example, the light emitting units 3, 6, 9, 21 respectively have light emitters 3A, 6A, 9A, 21A each capable of emitting and irradiating light of a predetermined wavelength and the light receiving units 4, 7, 10, 22 respectively have light-receiving cut filters 17, 18, 19, 24 for allowing transmission of a light in the predetermined wavelength and light receivers 4A, 7A, 10A, 22A for receiving the light transmitted through the respective light-receiving cut filters 17, 18, 19, 24 corresponding thereto.
With this feature, the light emitting units respectively have light emitters each capable of emitting and irradiating a light in the predetermined wavelength and the light receiving units respectively have light-receiving cut filters for allowing transmission of light in the predetermined wavelength and light receivers for receiving the light transmitted through the respective light-receiving cut filters corresponding thereto. Therefore, there is no need of employing a special construction as the light receiving unit. As a result, the invention may be embodied, with using a light emitter, a light receiver and a cut filter which are relatively inexpensive.
According to the present invention, as shown in FIGS. 1 and 3 for example, at least one of said light emitting units 3, 6, 9, 21 emits and irradiates near infrared light.
According to the present invention, at least one of said light receiving units 4, 7, 10, 22 receives near infrared light.
With these features, at least one of said light emitting units emits and irradiates near infrared light or at least one of said light receiving units receives near infrared light. Therefore, it is possible to detect e.g. the filled amount of the liquid, regardless of the color of the container or the color of the liquid filled inside the container.
Namely, in case the detection of the filled amount of the liquid or presence/absence of any foreign substance in the liquid or in the container or in the container forming material is effected by way of imaging the liquid-filling container by using a visible light having a wavelength of 400 nm to 700 nm as conventionally proposed, if the container has a dark color such as black, dark green or dark brown, as shown in a graph of FIG. 4 (transmittance for a glass thickness of 3 mm), the transmittance of the visible light becomes extremely low.
For this reason, when the visible light emitted from the light emitting unit is received by the light receiving unit, the portion of the visible light travelling outside the container is received substantially as it is or directly by the light receiving unit, so that the amount of received light for this area outside the container is large, whereas the amount of light corresponding to the container is extremely small. Then, since the inspection of the liquid surface of the liquid filled in the container or of the absence/presence of any foreign substance in the liquid or in the container or its material is to be effected for such area of extremely limited received light amount, the detection error becomes significant or the detection of the liquid surface or mixed foreign substance per se becomes very difficult. Further, even if the absolute light amount is increased to overcome this problem, improvement in the detection precision made possible by such measure is limited.
Further, even if the container per se does not have such dark color as black, dark green or dark brown, if the liquid filled therein has a dark color, the detection of foreign substance in the liquid becomes impossible. Moreover, if fine bubbles generated in association with the filling operation of the liquid are present near the liquid surface, the amount of light transmitted through the bubbles will be small due to the effect of diffused reflection of the light by the bubbles and also the amount of light transmitted through the liquid portion too will be limited due to the dark color, so that discrimination therebetween is difficult, thus impeding reliable detection of the liquid surface.
On the other hand, with the use of near infrared light having a wavelength of 700 to 900 nm, preferably 750 to 850 nm, even if the container has a dark color such as black, dark green or dark brown or if the filled liquid has a dark color or even if the container has a surface frosting treatment, there occurs no significant reduction in the transmittance of the near infrared light through the liquid-filling container. So that, significant reduction in the received light amount for the area corresponding to the liquid-filling container may be avoided advantageously.
Accordingly, various kinds of detection for the area corresponding to this container of the liquid surface level or of any foreign substance present in the liquid or in the container or the container material are made possible. As a result, the various conditions of the liquid-filing container can be reliably detected, regardless of the color of the container or the color of the liquid or regardless of presence/absence of bubbles near the liquid surface.
Incidentally, for imaging a liquid-filling container by irradiating light from the light emitting unit onto the container and receiving the transmitted light by the light receiving unit, or receiving the light by the light receiving unit, according to the present invention, the amount of received light at the area corresponding to the container is positively increased so as to reduce the difference in the received light amounts relative to that of the area corresponding to the outside of the container thereby to improve the detection precision. By irradiating the near infrared light alone or a greater amount of near infrared light component than visible light component of the light, a sufficient amount of near infrared light may be transmitted, depending on the color of the container or the color of the liquid filled therein. Or, by receiving the near infrared light component alone or a greater amount of near infrared component than the visible light component by the light receiving unit, a sufficient amount of near infrared light may be transmitted, depending on the color of the container or the color of the liquid filled therein.
According to the present invention, as shown in FIGS. 1 and 3 for example, each imaging device 2, 5, 8, 20 images a state of a liquid-filled container B which is conveyed one after another along a transport line 1.
With this characterizing, each imaging device images a state of a liquid-filled container which is conveyed one after another along a transport line. Therefore, for the number of liquid-filling containers being conveyed along the transport line one after another, various conditions thereof such as the filled amount, presence/absence of foreign substance in the liquid, presence/absence of foreign substance in the container or the container forming material, and the condition of the container mouth or attachment condition of a cap to the container mouth can be detected speedily and continuously.
According to the present invention, as shown in FIG. 1 for example, in the method of imaging a liquid-filling container or the apparatus for imaging a liquid-filling container, one of said plurality of imaging device 2, 5, 8 is a filled-amount detecting device 2 for detecting the filled amount of liquid W filled in the container B.
With this feature, one of said plurality of imaging devices is a filled-amount detecting device for detecting the filled amount of liquid filled in the container. Therefore, the filled amount of the liquid filled in the liquid-filling container may be detected. Especially, if near infrared light is used in this filled-amount detecting device, for the reasons described hereinbefore, even if the container has a dark color such as black, dark green or dark brown or if the filled liquid has a dark color or even if the container has a surface frosting treatment, the detection of liquid level is possible at the area corresponding to this container. As a result, the filled amount of the liquid may be detected reliably, regardless of the color of the liquid-filling container or the liquid or presence/absence of bubbles near the liquid surface.
According to the present invention, as shown in FIG. 1 for example, in the method of imaging a liquid-filling container or the apparatus for imaging a liquid-filling container, one of said plurality of imaging devices 2, 5, 8 is a liquid foreign substance detecting device 5 for detecting foreign substance present in the liquid filled in the container B.
With this feature, one of said plurality of imaging devices is a liquid foreign substance detecting device for detecting foreign substance present in the liquid filled in the container. Therefore, the presence/absence of foreign substance in the liquid filled in the liquid-filling container may be detected. Especially, if near infrared light is used in this liquid foreign substance detecting device, for the reasons described hereinbefore, even if the container has a dark color such as black, dark green or dark brown or if the filled liquid has a dark color or even if the container has a surface frosting treatment, the detection of the presence/absence of foreign substance in the liquid is possible at the area corresponding to this container. As a result, the presence/absence of foreign substance in the liquid may be detected reliably, regardless of the color of the liquid-filling container or the liquid or presence/absence of bubbles near the liquid surface.
According to the present invention, as shown in FIG. 3 for example, in the method of imaging a liquid-filling container or the apparatus for imaging a liquid-filling container, one of said plurality of imaging devices 8, 20 is a container/container-material foreign substance detecting device 20 for detecting foreign substance present in the container or in material forming the container.
With this characterizing feature, one of said plurality of imaging devices is a container/container-material foreign substance detecting device for detecting foreign substance present in the container or in material forming the container. Therefore, the presence/absence of foreign substance in the liquid-filling container or in the material forming the container may be detected. Especially, if near infrared light is used in this container foreign substance detecting device, for the reasons described hereinbefore, even if the container has a dark color such as black, dark green or dark brown or if the filled liquid has a dark color or even if the container has a surface frosting treatment, the detection of the presence/absence of foreign substance in the container or in the container material is possible at the area corresponding to this container. As a result, the presence/absence of foreign substance in the container or container material may be detected reliably, regardless of the color of the liquid-filling container or the liquid.
According to the present invention, in the method of imaging a liquid-filling container or the apparatus for imaging a liquid-filling container, one of said plurality of imaging devices 2, 5, 8, 20 is a container mouth detecting device 8 for detecting condition of a mouth of the container B or attachment condition of a cap C to the container mouth.
With this characterizing feature, one of said plurality of imaging devices is a container mouth detecting device for detecting condition of a mouth of the container or attachment condition of a cap to the container mouth. With this, needless to say, it is possible to detect condition of a mouth of the container or attachment condition of a cap to the container mouth by effectively utilizing the light reflected from the container mouth or from the cap. Moreover, even when the filled-amount detecting device, the liquid foreign substance detecting device and the container/container-material foreign substance detecting device are used at one time together, there occurs no interference therebetween, and the condition of a mouth of the container or attachment condition of a cap to the container mouth may be detected.
Incidentally, in the above description, reference marks and numerals were employed for facilitating reference to the accompanying drawings. It is understood that the provision of these marks and numerals is not to limit the invention to the constructions shown in the drawings.